Process for sizing textiles



United States Patent Ofifice 3,375,523 Patented Apr. 9, 1968 3,376,623 PRGCESS FOR SIZING TEXTILES Walter J. Katzbeck, Oak Park, lilL, and Earl G. King, Greenville, 5.6., assignors to Corn Products Company, New York, N .Y., a corporation of Delaware No Drawing. Fiied July 23, 1964, Ser. No. 384,783 1 Claim. ((31. 2872.6)

ABSTRACT OF THE DISCLOSURE Covers a method of warp sizing by coating textile fibers with a paste of a cross-bonded distarch phosphate having a Scott Viscosity within the range of grams/4040 seconds to about 40 grams/40-80 seconds. The fibers are then woven into a cloth which is desized.

This invention relates to a method for sizing textile materials. More particularly, this invention relates to a process for sizing textile materials with a cross-bonded distarch phosphate.

In the weaving of cloth, it is customary to size the yarn to impart the necessary strength and provide surface protection for the yarn so that it can withstand the mechanical strain of the weaving operation on the loom. In many cases, it is desirable to remove the size after the yarn is woven and before additional processing such as dyeing, and the like. Conventional starch sizes. are not readily removed from many textiles after the sizing operation, unless in the desizing treatment the starch is extensively hydrolyzed or otherwise degraded as by means of enzymes, acids or oxidants. Efiiuents from these desizing operations contain biologically oxidizable materials which create a problem in disposition. These wastes were formerly dumped into nearby bodies of Water, but many localities now have laws which prohibit sewerage of materials having a high biological oxygen demand (B.O.D.). Textile mills were thus faced with a choice of providing a sewage disposal plant for their plant eflluents or changing to the use of relatively costly sizing agents that have a relatively low B.G.D. value. Sizing agents with reasonably low 13.0.1). values, now being increasingly used, include certain chemical derivatives of starch such as for example, the hydroxyalkyl ethers of starch and the carboxymethyl ether of cellulose. These agents are expensive and do not solve the problem of stream pollution caused by dumping large quantities or organic matter into bodies of water; in fact, the total problem of pollution can be made more complicated by their usage since, being highly resistant to natural biological degradation, some of these agents persist for indefinitely long periods and, thus, contribute additional problems to efiiuent management.

Another problem arising from sizing textiles with conventional starches is high humidity. If the humidity is too high, the warps become sticky, so that the threads may cling to one another and break when conventional starches, such as oxidized, acid modified or hydroxyethyl starch, are used as sizing agents.

This invention not only overcomes the above described disadvantages of the prior art methods, but also presents considerable advantages over the prior art, as will be shown. According to the present invention, a cross-bonded distarch phosphate is used as the textile sizing agent. This cross-bonded distarch phosphate is made by treating an aqueous slurry of starch with a metaphosphate, polyphosphate or phosphorus oxychloride to form a crossbonded or inhibited starch. The reaction is usually cat-' alyzed with an alkaline reagent. Any type of starch may be used such as corn, tapioca, waxy maize, milo, and potato. The extent of cross-bonding may be determined by the Scott Viscosity of the cross-bonded distarch phosphate. This is done by determining the Scott Viscosity as set forth in Chemistry and Industry of Starch, R. W. Kerr, Academic Press, Inc., New York, 2nd edition, page 119. Cross-bonded distarch phosphates having 21 Scott Viscosity ranging from the 15 gram/40-80- seconds level to about the 40 grams/4080 seconds level are suitable for use in a textile sizing operation, in accordance with this invention. Cross-bonded or inhibited distarch phosphates undego restricted swelling upon cooking in water. The resulting pastes maintain a high, stable viscosity during prolonged cooking and circulation.

lrVhen a cross-bonded distarch phosphate is used as a textile size in accordance with the process of this invention, only half as much starch is required to give the same or better protection to textile fibers during weaving as when conventional starch products are used. Therefore, stream pollution caused by dumping desized liquor into the stream is reduced, in most cases, by about Furthermore, the cross-bonded distarch phosphates may be cooked in either batchwise or in continuous cookers. The pastes show no congelation in the size box and have excellent viscosity stability and will not form hard size or set-marks on the warps as do many conventional starches. No clinging or sticking of the warps is apparent when weaving fibers with the cross-bonded distarch phosphates. Films of the cross-bonded distarch phosphates do not become tacky at high humidity and are not embrittled at low moisture levels. Tensile strength, elongation and fiber lay of the cross-bonded distarch phosphates are equal to and ,in some cases, better than those of warps sized with conventional starches. The cross bonded distarch phosphates can be used to size all types of fibers. The cross-bonded distarch phosphates can be used to size warps at high temperatures as is the customary practice using conventional products and, in addition, the cross-bonded distarch phosphates can be used to size warps at low temperatures which cannot be done with most conventional starch products.

The following specific examples are given for purposes of illustration and are not to be considered as limiting the invention in any Way.

EXAMPLE I A cross-bonded corn distarch phosphate was made as follows: Twenty pounds, dry substance basis, of unmodified corn starch having a Scott Viscosity of 12 grams/ seconds were slurried in water to a concentration of 22 Baum (60 F./60 F.). Temperature of the slurry was adjusted to F. and 0.4 pound of sodium chloride was added and dissolved. The pH value of the slurry was adjusted from 4.5 to 10.2 by using a dilute solution of sodium hydroxide (0.08 pound dissolved in 1600 ml. water). A dispersion of 02 pound of sodium trimetaphosphate in ml. water was added and the reaction was allowed to proceed for about 2.5 hours to yield a cross-bonded distarch phosphate having a 15 gram/40-60 seconds Scott Viscosity range. Hydrochloric acid was added to the slurry 3 to adjust the pH value to about 4.5 and the starch was filtered and washed with water. The filter cake was dried to about 11% moisture and had a Scott Viscosity value of 15 grams/ seconds.

The above cross-bonded distarch phosphate was cooked in water for 15 minutes at 210 F. at a concentration of 0.5 pound per finished gallon, and then homogenized in conventional equipment at a pressure of 1500 p.s.i. The resultant paste at 205 F. was applied to carded cotton 22.6s warps in a textile mill using conventional slashing equipment at a speed of yards per minute. The warps were then dried by conventional means.

Warp size add-on averaged 7.5%. The dried warps had good hand and were smooth to the touch. During the entire slashing operation, no gelling of the starch size in the size box was observed, no hard size was formed nor found in the warps, and set-marks due to slasher shutdowns and startups were absent.

During the weaving operation, carried out in a room at 85% relative humidity, using the above dried warps, no fuzz-balling was observed; the warps did not cling or stick together in spite of the very moist atmosphere; no shedding of either the starch size from the fiber or of fiber itself was observed, indicating excellent fiber protection due to the cross-bonded distarch phosphate used.

EXAMPLE II An acid-modified starch having a Scott Viscosity of 15 grams/55' seconds was cooked at a concentration of 0.85 pound per finished gallon for about 15 minutes at 212 F. and then homogenized at 2000 p.s.i. to yield a paste with the same viscosity as that of the cross-bonded distarch phosphate of Example I.

This paste was applied to the same type of cotton warps using the same equipment, slashers and driers as in Example I. Warp size add-on averaged 13.5%.

Representative lots of both types of warps, from Examples I and II, were evaluated in a textile laboratory. The warps sized with the cross-bonded product had tensile strength and elongation characteristics equal to the warps sized with conventional starches; abrasion resistance of the cross-bonded starch sized warps was better than that of conventionally sized warps and fiber lay values were equal even though warp size add-on was much less for the cross-bonded product.

Both types of warps were placed under various conditions of relative humidity of 65% to 100% at F. Warps sized with the cross-bonded product did not become tacky or sticky until the relative humidity had been raised to about 100%. The conventionally sized warps became slightly sticky even at about 87% relative humidity showing that the cross-bonded starch film was much more resistant to high moisture conditions.

The warps sized with the conventional starch were woven in the mill under the same conditions employed for the cross-bonded starch of Example I. Some fuzzballing was observed and some clinging of the warps was noted when conventional starches were used because of their slight stickiness at relative humidity.

Both of the sized cloths were subsequently desized by conventional washing procedures; the cross-bonded product was removed from the cloth as readily as was the conventionally sized material.

EXAMPLE III A cross-bonded distarch phosphate was made according tothe procedure of Example I, except that phosphorus oxychloride was used instead of the sodium trimetaphosphate. Reaction conditions were similar with the exception that no salt was used in the reaction. Suflicient POCl size add-on. The following results were observed; no fuzzballing or warp tackiness, no shedding, good abrasion resistance and good fiber lay.

A modification of the Scott Viscosity procedure is used to further characterize the distarch phosphate ester prodnets and to differentiate them from conventional starches and other types of cross-bonded starches used as ethers. For customary Scott Viscosity determinations on starch products, the standard specified cooking time is 15 minutes. Cooking time, however, can be extended to whatever period is desired (for example, 90 minutes) so as to measure the effect of such prolonged heating on the viscosity stability of the starch product being evaluated. Regular Scott Viscosity is usually determined in starch products cooked in an aqueous system at a pH value of about 5.5. The pH value of the medium can be adjusted,

for example, to 3.5 with citric acid to determine the viscosity stability under the accelerating effect of low pH. This is demonstrated by the following example.

EXAMPLE IV Too thick.

The above results show that conventional starches,

when cooked under prolonged or acid conditions, lose vist cosity. Distarch ester phosphate products cooked under the same conditions do not lose viscosity but increase in viscosity under such conditions whereas the distarch ether becomes objectionably viscous. Whereas some viscosity increases will be offset by shear from pumping the hot slurry to and from the size box, too great an increase will eventually clog the lines.

EXAMPLE V This example shows the eifect of shearing time in a 1 Waring Blender on starch pastes having the following characteristics: Cone. 7%, cook time 45 min. at 210 F. and cook pH 5.5.

Hot Shear Viscosity: Brookficld cps. 210 F. Alter Shearing for Corn Starch Product of Example IV Various Times (Minutes) Distarch Phosphate Ester 280 430 160 Distarch Ether 1, 700 2, 200 2, 030 2, 500 Acid Modified Starch 260 150 90 70 The above results show that mechanical shear applied to pastes of conventional starches radically degrades the viscosity. Pastes of cross-bonded starches, when sheared in such an apparatus, show an increase in past viscosity followed by a decrease. This is especially apparent with the distarch phosphate esters. Pastes of distarch ethers on the other hand show an increase in viscosity on shearing, but viscosity remains at a high value and even increases on prolonged shearing. This is not a desirable result for a product which is to be used in textile applications such as that described above. A desirable product mustdisplay viscosity stability when cooked but must also be capable of being mechanically sheared to reduce its viscosity to a useable level without applying extraordinary means for so doing.

EXAMPLE VI Four hundred pounds (352 pounds dry substance) of unmodified corn starch were dispersed in water to about 22 Baum. Temperature was adjusted to F., and the following chemicals were added in order: 11 pounds sodium chloride, 1.5 pounds sodium hydroxide dissolved in water, and pounds of sodium trimetaphosphate dispersed in water. The reaction was allowed to proceed for about two hours to yield a product having a Scott Viscosity of 40 grams/64 seconds. The reaction was then stopped by adjusting the medium to a pH value of about 4.5 and the starch was filtered, washed and dried.

The resulting product was cooked in water at 212 for minutes at a concentration of 0.66 pound per finished gallon. The paste was applied directly onto cotton warps at 205 F. using conventional slasher equipment and then dried. Warp size add-on averaged 9.2%, as contrasted with 13% for conventional starches, and the warps felt very smooth.

The starch customarily used as a warp size in an acid hydrolyzed corn starch having a Scott Viscosity of 28.35 grams/SO-SS seconds and is dispersed in water at a concentration of one pound per finished gallon and cooked for about 150 minutes at 212 F. to reduce and stabilize its viscosity prior to application on warps at 205 F. Obviously, the distarch phosphate ester which requires only one-tenth the cooking time and performs as efficiently at about 40% less consumption is of great advantage to textile manufacturers.

The results of these examples, show that phosphate ester cross-bonded corn starch products ranging in Scott Viscosity from the 15 grams/40-8O seconds level to about the 40 grams/40-80 seconds level provided good protection to cotton warp fibers at about one-half the amount required when conventional starches are used.

We have found that corn starch products with less cross-bonding than that shown by the 15 gram crossbonded corn starch product of Example I, exhibit less viscosity stability on prolonged cooking and display much less shear stability and, therefore, are not as useful in the textile sizing process.

Example VI also shows that a highly cross-bonded product can be successfully applied to cotton warps using a cooked paste of the product without homogenization or other mechanical means for reducing viscosity. This product is particularly suitable for those manufacturers who do not have special equipment to modify starch viscosity since only a kettle is needed in which to prepare pastes.

EXAMPLE VII The procedure of Example VI was repeated except that the phosphated ester cross-bonded starch paste was cooked to about 120 F. and applied at this temperature to carded cotton warps. Warp size add-on was 8.8%. Results on slashing were similar to those of Example VI at 205 F. No congelation was observed in the size box; no set-marks or hard size was noted. These low temperature sized warps wove equally as well as those of Example VI sized at 205 F.

These results show that pastes of a cross-bonded starch product may be used without difficulty at a low as well as at a high temperature, giving good results in either case. Slashing warps at a low temperature is a very desirable feature for all textile manufacturers from the standpoint of safety to personnel, reduced corrosion of equipment, and improved washing conditions, besides having less deleterious eifects on fiber characteristics, i.e. low temperature sizing provides greater retention of fiber tensile strength, less elongation or stretch and economies in heating and cooking. A low-temperature sizing operation is not normally done today when conventional starches are used because the starches congeal at 120 F. and are entirely unusable at temperatures below 200 F. Congelation of size reduces overall warp protection, promotes hard size and set-marks.

EXAMPLE VIII Following the procedure of Example I, cooked, homogenized pastes of the 15 gram Scott Viscosity cross-bonded distarch phosphate were applied to the following types of fibers and fiber blends in various textile mills: carded cotton-50%; Avril; 65 polyester-35% combed cotton; 100% spun viscose rayon; glass fiber; 50% polyester-50% combed cotton; 65% polyester and 35% high wet modulus rayon; mixtures of polyacrylic, polyamide (nylon) and carded cotton.

No modifications of conventional equipment were necessary to employ the cross-bonded corn starch; protection of the above synthetic and synthetic-cotton blends was similar to that observed for cotton fiber. These results show that an ester cross-bonded product has wide application in practice, afiording an inexpensive size material which can be used at low concentration to give maximum protection to any type of warp fiber using about 50% less starch than ordinarily required.

When using conventional starch products on these fibers, warp size add-on ranges from about 13 to as high as 20%. In most such cases, simple, relatively inexpensive products such as acid hydrolyzed starches cannot be used; for adequate protection, manufacturers have had to use relatively expensive derivatized starch products such as hydroxyethyl ethers and products made from waxy corn or waxy sorghum starches or even more expensive totally synthetic agents.

EXAMPLE IX This example is given to show the absolute lack of tackinses of films of ester cross-bonded products compared to those of a conventional starch used for warp sizing when both are exposed to atmospheres where both the temperature and the relative humidity are high.

A 10% solids paste of the cross-bonded product of Ex-- ample I was applied to a thin glass disk inch in diameter. At the same time, a film 2 mils thick of the paste was applied with a Bird applicator to a 2 inch square of glass. These were conditioned for 24 hours and then the thin disk was attached to the stationary arm, and the square glass to the moveable arm in an Instron instrument. The films on the two plates were contacted for seconds and then pulled apart. Prior to and during this operation, the atmosphere around the Instron was adjusted with respect to both temperature and moisture evaluations made were based on the force required to separate the films at different temperatures and relative humidities. Films of a cross-bonded product did not stick to one another even when the atmosphere was saturated with water vapor at any temperature beween F. and 95 F. Films of conventional starch, for example, an acid hydrolyzed product having a Scott Viscosity of 15 grams/55 seconds, became sticky and tacky at 88% relative humidity, even at temperatures as low as F. These results are of great importance in textile practice. Present common practice with conventional starch products, although questionable as to its merits, is done at high relative humidities in the weave room to improve weavability. Thus, in most mills today, the air is actually highly saturated by spraying water into the weave room with equipment which is expensive to install and operate. Even though films of conventional starches become tacky at relative humidities around -90%, warps sized with these starches are woven under such conditions. When warps stick to one another, each individual warp will not be readily separated for efficient weaving. If warps stick to each other tenaciously, the warp threads, being relatively weak, will not open in the shed and will break. Warp breakages result in loom stoppages, thus alfecting weaving efiiciency.

Under conditions of high relative humidity, mill personnel are uncomfortable and equipment is rapidly corroded. Providing textile manufacturers with a cross-bonded starch product of such characteristics that the sized warps will not become sticky at a relative humidity of as high as is of great importance. Loom stoppages are eliminated when a cross-bonded starch is used at high relative humidities and increased efliciency'is obtained at low humidities.

We claim:

1. A Warp szing process which comprises the steps of coating textile fibers with a cooked paste of a crossbonded distarch phosphate having 21 Scott Viscosity within the range of 15 grams/40-80 seconds to about 40 grams/ 40-80 seconds, weaving said fibers into a cloth, and desizing the woven fibers.

8 References Cited UNITED STATES PATENTS 6/1963 Bode 117-139.5 8/1964 Hullinger et a1. 117165 X WILLIAM D. MARTIN, Primary Examiner.

T. G. DAVIS, Assistant Examiner. 

